An industry standard (hereinafter, Multi Source Agreement (MSA)) pluggable optical module is increasingly employed and has interfaces such as an external form and characteristics prescribed. This pluggable optical module enables the optical module to be inserted into and removed from a case (cage), and is demanded to have a simple cage shape and favorable assemblability, and to enable easy attachment and detachment with respect to the case. The optical module includes an optical transceiver, for example.
The optical module has an insertion/detachment port disposed in a front part and the front part of the optical module has a bail freely rotatably disposed for insertion/detachment operation of the optical module into/from the case. The optical module is removed from the cage by holding and pulling out a bail portion. The optical module is attached to the cage by pushing in the optical module toward the cage.
An engagement function is configured to work in conjunction with rotation of the bail and, when the optical module is attached to the cage, the bail is rotated to a position (attachment position) with the front part of the opening module opened, thereby engaging an engaging unit of the case and an engaging unit of the optical module with each other to fixedly hold the optical module in the cage. On the other hand, when the optical module is removed, the bail is rotated to a horizontal position (removal position) parallel to the optical module, thereby releasing the engagement between the cage and the engaging unit of the optical module so that the case can be removed from the optical module.
For such an optical module, a technique has been disclosed that gives a biasing force to the rotation of the bail by disposing an attaching/detaching mechanism such as a spring and a cam so as to fixedly hold the optical module to the cage while the bail is rotated to the attachment position (see, for example, Published Japanese-Translation of PCT Application, Publication Nos. 2007-522530 and 2005-522853).
However, a conventional attaching/detaching mechanism has a large number of components, which makes component cost high, and cannot easily be assembled. For example, since a bail and an engaging unit are different components, the dimensional tolerances of the components and the degrees of bending of the components affect assembly accuracy between the components, making improvement in yield difficult. Variation of assembly accuracy prevents the rotating state of the bail and the engaged state in the engaging unit from interlocking as designed, which may destabilize the engaged state of the optical module with the cage. Since a spring and a cam are necessary for the attaching/detaching mechanism, it takes time to incorporate these components.